This paper critically revisits the fundamental, defining notion of “project” in project studies. It examines extant approaches to defining projects and illuminates the ontological fuzziness of the main unit of analysis in project studies. Drawing on the notions of open and essentially contested concepts, the paper emphasizes the importance of studying how the project concept has been applied in empirical research. To advance the debate in this direction, two dimensions are emphasized: (1) the “project” as a realization of an object versus the “project” as an actor’s assignment, and (2) the “project” viewed as an empirical phenomenon versus the “project” used as an analytical lens, resulting in a typology of four distinct research approaches to the project concept. By discussing the approaches’ implications for research inquiries on projects and project management, the paper calls for more prudence when applying the “project” as unit of analysis in future empirical research. Consequently, the paper takes a step towards invigorating the once vivid debate on the core, defining concept within project studies.